The word “tokamak” is of Russian origin and means “toroidal chamber with magnetic coils”. This magnetic confinement system holds plasma in magnetic fields of toroidal shape. The first tokamak, the T-1, started operation in 1958 in Russia, and since then the greatest advances in thermonuclear fusion research have been achieved with tokamaks. JET, for many years the world’s largest tokamak, came closest to the scientific breakeven point in 1997, when it achieved Q = 0.67. Important tokamaks include JT-60SA, EAST and WEST, while JET and TFTR played major historical roles. ITER, which will be the world’s largest tokamak, is now being built in Cadarache, France.